Hematopoiesis
Terms
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- Site of blood production in 1st trimester
- Yolk Sac
- type of hgb in first trimester
-
ε and ζ
Epsilon and Zeta - Mesoblastic Period
-
1st trimester
yolk sac
detectable at 20 days gestation
primarily erythroid
epsilon and zeta hemeglobin - Site of blood production in 2nd trimester
-
Fetal Liver
(spleen, thymus, lymph also active) - Site of blood production in 3rd trimester
- Bone marrow
- Myeloid Period
-
3rd trimester
5th month gestation
bone cavities of central or peripheral skeleton
Hgb A1 appears (α and β chains)
Active Myelopoeisis -
Period of active myelopoeisis
(formation of blood cells other than erythroid) -
Myeloid Period
3rd trimester - Sites of Adult Hematopoeisis
-
Vertebral bodies
Sternum
Ribs
Pelvis
Skull, proximal epiphyseal of humerous and femur - Sites of Adult hematopoesis in times of stress
-
Extramedullary hematopoesis
Liver, spleen, etc -
Bone Marrow Histology
(stuff in BM) -
Fat
Blood Vessels
Trabecular bone
Hematopoietic islands - Cells in bone marrow
-
Hematopoietic cells
endothelial cells
adipocytes
osteocytes
stromal cells - Purpose of stromal cells in bone marrow
-
Specialized fibroblasts
Physical support for hematopoetic cells
Express adhesion molecules
Secrete growth factors - Totipotent stem cells
-
Cells capable of unlimited self-renewal and differentiation
Highly resistant to chemotherapy - CD34
- Surface antigen of totipotent stem cells
- Dysfunction leads to aplastic anemia or leukemia
- Totipotent Stem cells
- Multipotent stem cells
-
Derived from totipotent stem cells
Capable of extended self-renewal and differentiation - Progenitor Cells
-
aka colony stimulating units
Derived from multipotential stem cells
capable of limited self-renewal and differentiation
Responsive to hematopoeitic growth factors
Express differentiation antigens - Normoblasts
- RBC precursors
- Myeloblasts
- Granulocyte precursors
- Monoblasts
- Monocyte precursors
- Lymphoblasts
- Lymphocyte precursors
- Megakaryoblasts
- Platelet precursors
- Precursor Cells
-
First morphologically identifiable cells
Little if any self-renewal - Erythropoeitin
-
Synthesized in kidney
RBC growth factors
Synthesis increases in response to decreased rbc levels - GM-CSF
-
From endothelial cells, stromal cells, lymphocytes in marrow
Synthsis increased with decreased RBC's - G-CSF
-
From stromal cells in marrow
Synthesis increases in response to infections - SCF
- Stimulates totipotent and multipotent stem cells to differentiate
- Interleukins
-
Mediate communication betwn WBC's
increased synthesis in response to infections - Cytoskeletal proteins of RBC's
-
Spectrin
Ankyrin
Actin
Band 4.1 - Neutrophils
-
60-70% of WBC's
12-15 μm diameter
Usually 3 lobes - Types of granules in neutrophils
- Specific and Azurophilic
- Circulating lifespan of neutrophils
- 6-7 hours
- Lifespan of neutrophils in tissues
- 1-4 days
- Left shift
- Early mobilization of neutrophils from the bone marrow into peripheral blood
- Eiosinophils
-
2-4% circulating WBC's
12-15 μm diameter
increased in allergic reactions and parasitic infections - Eiosinophil granule contents
-
Acid phosphatase
Cathepsin
β glucouronidase - Basophils
-
1% circulation WBC's
Bilobed nucleus
12-15 μm diameter
Basophilic (dark) staining granules - Basophil granule contents
- Histamine and Heparin
- Monocytes
-
3-8% circulating WBC's
12-20 μm diameter
Live up to 4 days in circulation, then enter tissue and differentiate into macrophages
Phagocytize opsonized bacteria
Secrete cytokines
Have Fc recepters - Lymphocytes
-
20-25% circulation bacteria
b cells-15%
Null Cells-5%
t cells-80% - Platelets
-
No nucleus
pinch off from megakaryocytes in BM
7-10 days in circulation
contain granules
involved in clot formation - clinical indications for bone marrow biopsy
-
-unexplained cytopenia
-atypical circulating cells
-hematologic neplasias - Normal Myeloid:erythroid ratio
- About 1.5-3:1
- Normal RBC value for men
- 4.3-5.9 x 10^13/L
- Normal RBC value for women (direct)
- 3.5-5.0 x 10^13/L
- Normal WBC for men and women (direct)
- 5.0-11.0x 10^9/L
- Normal HGB for men (direct)
- 13.6-17.2 g/dL
- Normal HGB for women (direct)
- 12.0-15.0 g/dL
- Normal HCT for males(indirect)
- 39-49%
- Normal HCT for women (indirect)
- 33-43%
- Normal MCV (direct)
- 80-100 fL
- Normal MCH (indirect)
- 26-34 pg
- Normal MCHC (indirect)
- 30-36 pg
- Normal RDW (red cell distribution width) ((direct))
- 11.5-14.5
- Normal Platelet value
- 105-450 x 10^9/L
- Normal WBC Values
-
Neutrophils 60-70%
Eosinophils 2-4%
Basophils-<1%
Lymphocytes 20-25%
Monocytes 3-8% - Rule of 3's
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RBC's X 3= Hgb ± 3
Hgb x 3=Hct ± 3